The invention relates to a wet developing process for electrophotography and an apparatus therefor.
While both dry and wet developing means are known for electrophotography, i.e., electrostatic photography and electrostatic recording, the invention is particularly concerned with a wet developing process and apparatus therefor in which a developing solution is used as a developer.
The conventional wet developing process using a developing solution comprises maintaining a supply of the developing solution in a dish-shaped vessel into which an exposed photosensitive or recorded recording sheet is fed for passage through the developing solution to effect the developing process, or comprises flushing a developing solution across an exposed photosensitive or recorded recording sheet which is fixed.
However, in such developing techniques, the developing solution is supplied to both surfaces of the sheet to be developed, namely, the photosensitive surface (the surface of a photoconductive layer) or the recording surface (the surface of an induction layer) which has been exposed or recorded as well as the rear surface, which results in the disadvantage of marring the rear surface of the sheet due to the attachment thereto of the developer.
In a wet developing process, the developing solution must be well stirred before it is supplied to the sheet. This is because the developing solution is used as the carrier for a toner powder mixed therein as is known, so that unless it is well stirred upon developing, there cannot be achieved a uniform supply of toner powder to the surface to be developed, which results in the non-uniformity of development. For these reasons, it is established that the higher the speed of relative movement between the developing solution and the surface to be developed, the better the result obtained. On the other hand, it is apparent that only one surface of the sheet need be developed. Consequently, the supply of the developing solution to both surfaces is wasteful.